1. Field of the Invention
This invention relates to electromechanical relays. In particular, it relates to the construction of miniature electromechanical relays intended for use on circuit boards.
2. Description of the Prior Art
Electromechanical relays have found wide and varied applications in the Telecommunications and Electronics Industry. Although solid state devices have recently replaced relays in many telecommunications and electronic systems, electromechanical relays still offer many advantages in terms of cost and reliability in electrical circuit applications.
Electromechanical relays generally comprise an electromagnet, armature and contact assemblies wherein the energization of the electromagnet actuates the armature assembly to control the operation of the contact assembly thereby engaging and disengaging contacts to control external electrical circuitry coupled with the relay. In modern technology, miniaturization of components have resulted in large numbers of components being mounted on circuit boards. Since space on circuit boards is at a premium, electromechanical relays have been reduced in size so as to require only a small amount of mounting space on a circuit board. As the size of components have decreased and the number of electrical circuits appearing on a circuit board increased, the electrical current requirements for circuit boards have also been decreased thereby requiring the development of low current electromechanical relays.
A problem arises in the development of miniature and low current electromechanical relays in that the operating sensitivity of an electromechanical relay is affected by the reduction in size of the relay electromagnet apparatus and the amount of electrical current required to activate the relay armature. For example, relay armatures in previous miniature electromechanical relays require an elaborate design of spring members to hold the armatures in position with respect to the electromagnet. Such elaborate spring members require a large relay structure and an increase of electrical current to activate the armature to overcome the spring tension force thereby lowering the operating sensitivity of the relay.
Accordingly, a need exists for a miniature low current electromechanical relay having a high degree of operating sensitivity. A need also exists for an electromechanical relay requiring a small mounting space on a circuit board and a small amount of electrical current to activate an armature to engage and disengage contacts for controlling external electrical circuitry.